from typing import List


class Solution:
    def findRepeatNumber(self, nums: List[int]) -> int:
        set1=set()
        for i in range(len(nums)):
            if nums[i] not in set1:
                set1.add(nums[i])
            else:
                return nums[i]



if __name__ == '__main__':
    s=Solution()
    list1=[2, 3, 1, 0, 2, 5, 3]
    print(s.findRepeatNumber(list1))